Fill in Table 5.1 to indicate the total number of unpaired electrons in the 3d and 4s orbitals for an isolated gaseous Cu atom and a $\text{Cu}^{2+}$ ion.
The 3d orbitals in an isolated $\text{Cu}^{2+}$ ion are degenerate. Complete the diagram to compare the energies of the 3d orbitals in an isolated $\text{Cu}^{2+}$ ion and in $\text{Cu}^{2+}$ within a tetrahedral complex.
Explain why transition elements can act as catalysts.
Since $\text{CN}^-$ is a monodentate ligand, Table 5.2 gives details of two complex ions that contain only $\text{CN}^-$ as ligands. Complete Table 5.2.
The complex ion $[\text{Au} (\text{CN})_2\text{Br}_2]^-$ shows geometrical (cis/trans) isomerism. Draw trans-$[\text{Au}(\text{CN})_2\text{Br}_2]^-$ and state its shape and the Br-Au-Br bond angle.
An impure sample of a vanadium(V) compound with mass $0.250\,\text{g}$ is dissolved in aqueous acid. The solution contains $\text{VO}_3^-$ ions. An excess of zinc is then added to the solution. All of the $\text{VO}_3^-$ ions are reduced to $\text{V}^{2+}$ ions and Zn atoms are oxidised to $\text{Zn}^{2+}$ ions. The excess zinc is removed and the resulting solution is titrated with acidified $\text{MnO}_4^-$. The end-point is reached when $22.5\,\text{cm}^3$ of $0.0750\,\text{mol dm}^{-3}$ $\text{MnO}_4^-$ has been added. A redox reaction occurs and all of the $\text{V}^{2+}$ reacts to form $\text{VO}_3^-$. $3\text{MnO}_4^- + 5\text{V}^{2+} + 3\text{H}_2\text{O} \rightarrow 3\text{Mn}^{2+} + 5\text{VO}_3^- + 6\text{H}^+$. Calculate the percentage by mass of vanadium in the $0.250\,\text{g}$ impure sample. Assume that the impurities contain no vanadium ions. Show your working.
Complete the equation for the reaction of acidified $\text{VO}_3^-$ ions with Zn metal. $\ldots\ldots\,\text{VO}_3^- + \ldots\ldots\,\text{Zn} + \ldots\ldots\ldots\ldots\ldots\ldots \rightarrow \ldots\ldots\,\text{V}^{2+} + \ldots\ldots\,\text{Zn}^{2+} + \ldots\ldots\ldots\ldots\ldots\ldots$